The present invention relates to an ink jet head which is elongated by arranging a plurality of element substrates for effecting printing by ejecting liquid, and a manufacturing method therefor. It further relates to a device provided with the ink jet head.
Recently, an ink jet print type is widely used because the noise is low and because the high speed recording is possible. Among various types of ink jet printers, an ink jet head wherein thermal energy is applied to the ink by which the state change is produced in the ink, and the ink is ejected by the pressure resulting from thermal-expansion of the resultant gas (bubble jet type), is advantageous in that the responsivity to the print signal is high, and high density arrangement of the ejection outlets is relatively easy.
Recently, the data amount to be printed out increases. Particularly, when graphic data are to be printed out, the demand for the high speed print is increasing because the data amount in huge in that case.
Accordingly, an ink jet head of so-called full line type of the bubble jet type wherein ejection outlets and electrothermal transducers are arranged over the entire width of the printing material and an ink jet device having such an ink jet head, are expected as being the ones which permit the high speed printing.
As for such a full line type ink jet head, a method wherein all of the electrothermal transducers are formed in one substrate (heater board). However, in that case, if only one electrothermal transducer of the electrothermal transducers is defective, the entire substrate is not usable, with the result of very low yield. So, in a conventional full line type ink jet head, a plurality of heater boards having electrothermal transducers are combined. An a plurality of electrothermal transducers each having a relatively small number of electrothermal transducers such as 32-128 transducers, are supported on a supporting member at intervals matching the arrangement density of the nozzle. By doing so, even if one electrothermal transducer is defective, one heater heater board having the defective electrothermal transducer is exchanged. Additionally, the size of the heater board per se is small so that the manufacturing of the heater board per se is easy. Accordingly, the yield is remarkably improved. Such a structure is proposed in Japanese Laid Open Patent Application No. HEI-2-212162, for example.
By using the construction, the above-described advantages can be enjoyed, but another problem arises. With the above described construction, since a plurality of of heater boards are arranged in a supporting member, the arrangement accuracy is significantly influential to the printing quality. Conventionally, the arrangement accuracy is determined by the connection between the supporting member and the heater board or by the direct connection between the heater boards, and therefore, the processing accuracy of each construction member has to be strictly controlled. This also reduces the yield. When foreign matter is present between the construction members, the arrangement accuracy decreases with the result of influence to the printing quality. When the foreign matter is deposited between the heater board and the base plate, a step is formed on the heater forming the heater board with the result of gap in the contact plane between the heater board and the top plate. The gap may bring about cross-talk between adjacent nozzles with the result of improper printing.
Accordingly, it is a principal object of the present invention to provide stabilized printing without cross-talk by preventing gap formation between the heater board and the top plate. According to an aspect of the present invention, a supporting member for supporting the heater boards have recesses.
More particularly, there is provided an ink jet head manufacturing method wherein a plurality of substrates provided with ejection energy generating elements for generating energy for ejecting ink, are arranged on a supporting member, and a top plate is mounted on the substrate to cover all of the substrates to form ink flow paths, the improvement residing in that the supporting member is provided with recesses at a supporting portion for supporting the substrates, and an adhesive material is supplied into the recesses, and thereafter, the substrate is placed on the supporting member.
According to this aspect, the heater boards are independently supported by a supporting portion, which is provided with recesses. Thus, the contact area between the heater boards and the base plate is decreased, so that the step on the heater board resulting from the foreign matter deposited to the contact surfaces is prevented from being formed, and therefore, an ink jet head having high reliability without improper printing such as cross-talk, can be provided.
These and other objects, features and advantages of the present invention will become more apparent upon a consideration of the following description of the preferred embodiments of the present invention taken in conjunction with the accompanying drawings.